Injection molding is a common manufacturing process for producing plastic parts. Typically, material is fed into a heated barrel, mixed, and forced into a mold cavity where it cools and hardens to the configuration of the cavity. The molds are usually made of metal and precision-machined to form the features of the desired part. Injection molding is widely used for manufacturing a variety of parts, from the smallest component to entire body panels of cars.
In some applications, the plastic is molded over inserts to form a composite part. For example, the plastic can be molded around a stamped and formed metal part to form a composite plastic and metal part. The metal inserts can be, for example, a conductive lead, a fastener or a bushing. The result is a tightly bonded insert in the plastic part. By combining the physical strength of resin and metal inserts, insert molding can yield smaller and lighter components compared to parts manufactured using adhesive or soldering techniques. If multiple inserts are molded in a single injection molded part, however, it can be labor intensive to align each of the inserts with respect to each other and to dimensions of the finished product. Often this requires the manual alignment of each of the inserts in the mold prior to the injection process. The manual alignment can be more difficult if the inserts are very small and difficult to handle. If the dimension tolerances are very tight, this alignment process can be a significant factor in the production efficiency of the overall manufacturing process.